The use of baits to control the populations of insect pests is well known. To be effective, a bait must contain a compound that is lethal when ingested by an insect, and further, must attract the targeted types of insects and promote ingestion of a lethal amount of the insect-killing compound whenever the bait is encountered by a targeted insect. Most insect-killing compounds, including Boric Acid (H3BO3), are not themselves attractive to insects, and are not generally ingested by insects as food. This means that an effective insect bait must generally contain other compounds in addition to the insect-killing compound, the other compounds having the purpose of attracting insects and promoting ingestion of the insect-killing compound.
The use of Boric Acid as an insect-killing compound is well known in the prior art, the United States patent literature including the following documents: U.S. Pat. No. 1,636,688 (Harris, Jul. 26, 1927); U.S. Pat. No. 4,988,516 (Herring, Jan. 29, 1991); U.S. Pat. No. 1,029,203 (Jun. 11, 1912); and U.S. Pat. No. 4,438,090 (Brite, Mar. 20, 1984), and the foreign patent literature including the following: 0067209 (1984; JP); 0155303 (1984; JP); and 4654 (1899; GB). As an insect-killing compound, boric acid has the very significant advantages over alternative compounds of having very low toxicity toward humans and other mammals, and of low cost. Boric acid is not specifically attractive to insects, however, and is not generally regarded as food by insects. To take advantage of boric acid's insect killing properties, it must be incorporated into a bait with at least one other other compound that is attractive to insects, and that is regarded as food by insects.
Various bait compositions in which boric acid serves as the insect-killing component have been suggested. In the case of Herring (U.S. Pat. No. 4,988,516; 1988), it is recommended that boric acid be incorporated into a flat patty composed of white wheat flour, white vegetable shortening, chopped onions, white cane sugar, and water. While this formulation might be somewhat effective as an insect bait, it suffers from unnecessary complexity and relatively high cost. Patties must be replaced after only one month due to spoilage. The biggest drawback of this bait is that upon encountering a bait patty, an insect would have the option of ingesting some part of the patty, such as the chopped onion, while leaving the boric acid uningested. No insect bait in the prior art, whether using boric acid or some other compound for its insect-killing ability, accomplishes the critical tasks of attracting sweet-eating insects, and encouraging insects to ingest a lethal amount of the lethal compound upon every encounter with the bait, as effectively as the bait described by the current disclosure.
The current invention takes advantage of the unsurpassed ability of caramelized sugar to attract sweet-eating insects such as cockroaches, water bugs, and several types of ants. Further, caramelized sugar is a powerful feeding stimulus for these insects. Whenever a sweet-eating insect encounters small particles of boric acid coated with caramelized sugar, the caramel coating ensures that a lethal amount of the boric acid will be ingested by the insect. In addition to having unrivaled efficiency in killing sweet-eating insects, the current invention also has the advantages of being able to use boric acid as the insect-killing compound in the preferred embodiment, and of having a simple, low cost formulation.